BACKGROUND: The metacarpophalangeal (MCP) joint\'s collateral ligaments have been extensively debated, with no clear consensus on their mechanics. Understanding their function is crucial for comprehending joint movement and stability.
METHODS: A thorough search was conducted across databases, including PubMed, Scopus, Cochrane library and grey literature. A total of 59 articles were identified, and after rigorous evaluation, six articles were included in the review.
RESULTS: The analysis underscores two principal findings. Firstly, the principal and accessory collateral ligaments exhibit consistent tension influenced by the MCP joint\'s position. This tension varies across different sections of the ligaments. Secondly, the ligaments\' interaction with the joint structure plays a pivotal role in defining the range of motion of the joint.
CONCLUSIONS: Preliminary findings from this review indicate that MCP joint collateral ligament tension varies with joint position. Increased tension in the principal collateral ligament during flexion and isometric behavior of its volar portion in extension are observed. The accessory ligament may tighten during extension. The shape of the metacarpal head appears to influence this tension. These insights, while informative, call for further detailed research to deepen our understanding of MCP joint mechanics.

There is an increasing rate of procedures being performed for concomitant injuries during anterior cruciate ligament (ACL) surgery. Few studies have examined risk factors for these associated injuries in young patients.
There are patient-related factors predictive of concomitant knee pathology that differ between age-based cohorts.
Cross-sectional study; Level of evidence, 3.
Natural language processing was used to extract clinical variables from available notes of patients undergoing ACL surgery between 2000 and 2020 at a single institution (5174 ACL surgeries; mean age, 17 ± 4 years; 53.1% female; accuracy, >98%). Patients were stratified to pediatric (5-13 years), adolescent (14-19 years), and young adult (20-35 years) cohorts. Logistic regression was used to determine predictors of concomitant injury to the menisci, medial collateral ligament (MCL), posterolateral corner (PLC), and posterior cruciate ligament (PCL).
Between 2000 and 2020, 54% of pediatric, 71% of adolescent, and 70% of adult patients had ≥1 concomitant soft tissue injury. In children and adolescents, increased age was consistently predictive of sustaining a concomitant injury (P < .02). Female children had increased odds of concomitant medial meniscal injury, while female adults had decreased odds (P≤ .046). Adolescent and adult female patients had decreased odds of concomitant lateral meniscal injury (P≤ .027). Female children had increased odds of injury to the MCL (P = .015), whereas female children and adolescents had decreased odds of PCL injury (P≤ .044). Adolescents undergoing revision ACL surgery had increased odds of meniscal injury (P≤ .001) and decreased odds of concomitant MCL injury (P = .028). Increased body mass index (BMI) was associated with increased odds of concomitant medial meniscal injury in all cohorts (P≤ .041), lateral meniscal injury in adults (P = .045), and PLC injury in children (P = .016). Contact injuries were associated with increased odds of MCL injury in adolescents (P = .017) and PLC injury in adolescents and adults (P < .014).
These findings support the hypothesis, as there were multiple factors that significantly affected the risk of concomitant injuries that differed between cohorts. Increased age, BMI, and contact injury history were generally associated with increased odds of sustaining a concomitant injury, whereas female sex and revision ACL surgery had mixed effects. Further studies are essential to investigate the sex-based differences in risk for concomitant injuries and to develop tailored treatment plans that minimize the risk of secondary ACL injury.

An intricate and unique combination of ligamentous, fibrocartilaginous, and osseous structures stabilize the thumb metacarpophalangeal joint. Both ultrasound and high-resolution magnetic resonance imaging are extremely useful in evaluating these critical structures. This article reviews common injuries of the thumb metacarpophalangeal joint, while highlighting the merits, limitations, and pitfalls of the two imaging modalities. A clear appreciation of each method, paired with anatomic knowledge, will lend greater confidence and accuracy to diagnosing impactful injuries and guiding intervention.

The purpose of this study was to develop injury risk functions (IRFs) for the anterior and posterior cruciate ligaments (ACL and PCL, respectively) and the medial and lateral collateral ligaments (MCL and LCL, respectively) in the knee joint. The IRFs were based on post-mortem human subjects (PMHSs). Available specimen-specific failure strains were supplemented with statistically generated failure strains (virtual values) to accommodate for unprovided detailed experimental data in the literature. The virtual values were derived from the reported mean and standard deviation in the experimental studies. All virtual and specimen-specific values were thereafter categorized into groups of static and dynamic rates, respectively, and tested for the best fitting theoretical distribution to derive a ligament-specific IRF. A total of 10 IRFs were derived (three for ACL, two for PCL, two for MCL, and three for LCL). ACL, MCL, and LCL received IRFs in both dynamic and static tensile rates, while a sufficient dataset was achieved only for dynamic rates of the PCL. The log-logistic and Weibull distributions had the best fit (p-values: >0.9, RMSE: 2.3%-4.7%) to the empirical datasets for all the ligaments. These IRFs are, to the best of the authors\' knowledge, the first attempt to generate injury prediction tools based on PMHS data for the four knee ligaments. The study has summarized all the relevant literature on PHMS experimental tensile tests on the knee ligaments and utilized the available empirical data to create the IRFs. Future improvements require upcoming experiments to provide comparable testing and strain measurements. Furthermore, emphasis on a clear definition of failure and transparent reporting of each specimen-specific result is necessary.

Introduction Basketball players are at increased risk of thumb collateral ligament injury (ulnar collateral ligament (UCL) and radial collateral ligament (RCL)). Methods The National Basketball Association (NBA) players with thumb collateral ligament surgery were identified using publicly available data. Performance statistics, ligament injuries (UCL or RCL), return to sport (RTS) time, laterality, and injury dates were recorded. Cases were matched 1:1 with controls based on age (±1 year), body mass index (BMI), NBA experience (±1 year), and performance statistics prior to the index date. RTS was defined as playing in one NBA game postoperatively. Career longevity was evaluated. Summary statistics were calculated, and Student\'s t-tests (ɑ = 0.001) were performed. Results All 47 players identified with thumb collateral ligament surgeries returned to sport. Thirty-three players (age: 26.9 ± 3.0) had one year of postoperative NBA experience for performance analysis. Career length (case: 9.6 ± 4.1, control: 9.4 ± 4.3, p > 0.001) was not significantly different from controls (p > 0.001). The same season time to RTS (n = 20) was 7.1 ± 2.4 weeks. Off-season or season-ending surgery (n = 13) RTS time was 28.4 ± 18.7 weeks. Neither thumb collateral ligament (UCL, n = 7; RCL, n = 10; unknown, n = 16) had an identifiable difference between the groups when evaluating career length. Career length, games/season, and performance were not different for players who underwent surgery on their dominant thumb (63.6%, 21/33) compared to controls (p > 0.001). Conclusion RTS rate is high in NBA athletes undergoing thumb collateral ligament surgery. Players do not experience decreased performance or career length due to thumb collateral ligament surgery, regardless of a dominant or non-dominant thumb injury.

A Stener-like lesion is defined as the interposition of the sagittal band between the torn collateral ligament of the metacarpophalangeal (MCP) joint of a finger and its origin or insertion. Owing to the rarity of this injury, standardized protocols on the diagnosis and care of these injuries are not currently available. PubMed Central and Google Scholar were searched for published studies from 1962 to 2022. Inclusion criteria admitted any injury of the MCP joints of any nonthumb fingers involving a torn collateral ligament with sagittal band injury that trapped the collateral ligament. Eight studies were ultimately included in our analysis and contained 11 cases of Stener-like lesions. Eight of the 11 cases presented radial collateral ligament injury to the ring and little fingers. All 11 cases presented showed that detailed physical examination was a primary step in diagnosis of these lesions. Metacarpophalangeal joint laxity was present in all cases reported. Imaging-aided diagnosis was used in majority of the cases presented and included arthrography, ultrasound, or magnetic resonance imaging. All cases presented in this review were managed surgically. Following surgical repair, a majority of authors opted to use immobilization techniques immediately postoperatively. As awareness of this injury pattern increases, a standardized treatment algorithm may develop.

BACKGROUND: Ruptured finger distal interphalangeal (DIP) collateral ligament is a rare injury, with controversial treatment until the present. Our case series aimed to demonstrate feasible surgical intervention using a mini anchor.
METHODS: The present study includes four patients with ruptured finger DIP collateral ligaments who received primary repair in a single institute. They have suffered from joint instability due to ligament loss caused by infection, motorcycle accidents, and work-related accidents. All patients were operated on similarly using a 1.0 mm mini anchor for ligament reattachment.
RESULTS: The finger DIP joint range of motion (ROM) was documented in all patients during follow-up. Joint ROM recovered to almost normal degrees, and the pinch strength recovered to > 90% compared to the contralateral side in all patients. Additionally, collateral ligament re-rupture, DIP joint subluxation or re-dislocation, and infection were not noted during follow-up.
CONCLUSIONS: Ruptured finger DIP joint ligament requiring surgery is usually based on a combination with other soft tissue injuries and defects. However, repair with a 1.0 mm mini anchor is a feasible surgical intervention to reattach the ligament with minimal complication.

The response of soft tissue to loading can be obtained by strain assessment. Typically, strain can be measured using electrical resistance with strain gauges (SG), or optical sensors based on the digital image correlation (DIC), among others. These sensor systems are already established in other areas of technology. However, sensors have a limited range of applications in medical technology due to various challenges in handling human soft materials. The aim of this study was to compare directly attached foil-type SG and 3D-DIC to determine the strain of axially loaded human ligament structures. Therefore, the medial (MCL) and lateral (LCL) collateral ligaments of 18 human knee joints underwent cyclic displacement-controlled loading at a rate of 20 mm/min in two test trials. In the first trial, strain was recorded with the 3D-DIC system and the reference strain of the testing machine. In the second trial, strain was additionally measured with a directly attached SG. The results of the strain measurement with the 3D-DIC system did not differ significantly from the reference strain in the first trial. The strains assessed in the second trial between reference and SG, as well as between reference and 3D-DIC showed significant differences. This suggests that using an optical system based on the DIC with a given unrestricted view is an effective method to measure the superficial strain of human ligaments. In contrast, directly attached SGs provide only qualitative comparable results. Therefore, their scope on human ligaments is limited to the evaluation of changes under different conditions.

OBJECTIVE: The objectives of the present study were to investigate the length change in different bundles of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) during lunge, and to evaluate their association with Knee Society Score (KSS) following medial-pivot total knee arthroplasty (MP-TKA).
METHODS: Patients with unilateral MP-TKA knees performed a bilateral single-leg lunge under dual fluoroscopy surveillance to determine the in-vivo six degrees-of-freedom knee kinematics. The contralateral non-operated knees were used as the control group. The attachment sites of the sMCL and LCL were marked to calculate the 3D wrapping length. The sMCL and LCL were divided into anterior, intermediate, and posterior portions (aMCL, iMCL, pMCL, aLCL, iLCL, pLCL). Correlations between lengths/elongation rate of ligament bundles from full extension to 100° flexion and the KSS were examined.
RESULTS: The sMCL and LCL demonstrated relative stability in length at low flexion, but sMCL length decreased whereas LCL increased with further flexion on operated knees. The sMCL length increased at low flexion and remained stable with further flexion, while the LCL length decreased with flexion on the contralateral non-operated knees. The lengths of aMCL, iMCL, and pMCL showed moderate (0.5 < r < 0.7, p < 0.05) negative correlations with the KSS, and the lengths of aLCL, iLCL, and pLCL were positively correlated with the KSS at mid flexion on operated knees (p < 0.05). The elongation rates of aLCL, iLCL, and pLCL were negatively correlated with the KSS at high flexion on operated knees (p < 0.05). However, no significant correlations between the length of different bundles of sMCL or LCL with KSS were found on contralateral non-operated knees.
CONCLUSIONS: The elongation pattern of sMCL/LCL on MP-TKA knees showed differences with contralateral non-operated knees. The sMCL is tense at low to middle flexion and relaxed at high flexion, while LCL is relaxed at low to middle flexion and tense at high flexion following MP-TKA. Medial stability and proper lateral flexibility during mid flexion were associated with favorable postoperative outcomes in MP-TKA patients. In contrast, lateral relaxation at deep flexion should be avoided when applying soft-tissue balancing in MP-TKA.
METHODS: Level III.

The metacarpophalangeal (MCP) joint is surrounded by various structures critical to its stability and function. Though the ligamentous injury to the digits is common, rupture of the metacarpophalangeal collateral ligament and a sagittal band of the same finger is not well represented in the literature. We report a chronic case of a concurrent metacarpophalangeal collateral ligament and sagittal band injury. Though surgery would have been the most appropriate treatment soon after the injury, restrictions on elective procedures due to the COVID-19 pandemic precluded surgical treatment. The patient was alternatively treated with buddy tape, and a close follow-up was done. This is the first reported case of a concurrent metacarpophalangeal collateral ligament, and sagittal band injury successfully treated using nonoperative management.